Method for manufacturing a composite material status sleeve

Abstract

The method of manufacturing a status sleeve begins with using automated fiber placement to wrap a cylindrical mandrel with a heated prepreg tape. The prepreg tape has continuous fiber reinforcements within a polymer matrix. Next, the cylindrical mandrel is cooled and removed from the wrapped prepreg tape to obtain an unfinished cylindrical status sleeve. Each end of the unfinished status sleeve is trimmed. Next, a cylindrical fixture is used to abut first and second end rings to the first and second ends of the trimmed status sleeve, respectively. The first and second end rings are of the same material as the polymer matrix of the prepreg tape. Finally, the first and second rings are laser welded or fusion bonded to the first and second ends of the trimmed status sleeve.

Description

Technical Field

[0001] Cross - Reference to Related Applications This non - provisional application claims priority based on Provisional Application No. 63 / 365,308, filed on May 25, 2022, the entire content of which is hereby incorporated by reference in its entirety into this specification.

[0002] The present invention generally relates to stator sleeves used in electric motors. More particularly, the present invention relates to a method for manufacturing a composite stator sleeve used in a high - performance electric motor having a liquid - cooled stator.

Background Art

[0003] Generally speaking, an electric motor has several important components that enable it to efficiently and effectively convert electrical energy into mechanical energy. Each component facilitates an important interaction between the magnetic field of the motor and the current flowing through its wire windings, helping to generate force in the form of rotation of the shaft. The mechanical energy generated by this rotation of the shaft helps to keep an electric vehicle running or to smoothly maintain the operation of a factory. These components can include a rotor, a stator, bearings, windings, and an air gap.

[0004] Rotor. The rotor is the moving part of an electric motor. It rotates the shaft that supplies the mechanical power described above. In a common configuration, the rotor has conductors embedded in it, and current flows through these conductors, and this current interacts with the magnetic field of the stator to generate a force that rotates the shaft. However, in some rotors, permanent magnets are attached, and it is the stator that holds the conductors.

[0005] Stator and Stator Core. The stator is the fixed part of the electromagnetic circuit of the motor and usually consists of either windings or permanent magnets. The stator core is composed of a number of thin metal sheets called laminations. The laminations are used to reduce the energy losses that would occur if a solid core were used.

[0006] Bearings. The rotor of an electric motor is supported by bearings that enable it to rotate on its axis. These bearings are supported by the motor housing. The motor shaft extends outside the motor through the bearings, where the load is applied. Since the load force is applied beyond the outermost bearing, the load is said to be "overhung".

[0007] Windings. A winding is a wire wound in a coil, usually wound around a laminated soft iron core, and forms magnetic poles when excited by an electric current. Electric motors have two basic magnetic field pole configurations: salient pole and non-salient pole. In a salient pole motor, the magnetic field of the pole is generated by the winding wound around the pole below the pole face. In a non-salient pole motor, the windings are distributed in the pole face slots.

[0008] Air gap. Although not a physical component, the air gap is the distance between the rotor and the stator. The air gap of a motor has an important effect. Generally, a large gap has a strong adverse effect on performance, so the air gap should be as small as possible. This is the main reason for the low power factor when the motor operates. Since the magnetizing current increases with the air gap, the air gap needs to be minimized. However, a very small gap may cause mechanical interference problems.

[0009] High-performance electric motors can generate a lot of heat, especially in the conductors. Therefore, many high-performance electric motors are configured with permanent magnets attached to the rotor and the stator holding the conductors. Then, liquid cooling can be used to directly cool the conductors, resulting in a liquid-cooled stator. A stator sleeve can be used to separate the stator from the rotor and enable the use of a fluid coolant. Such liquid-cooled motors can be used in applications such as e-mobility where high efficiency and weight-to-power output are important. Applicable inner-rotor / outer-stator motors include, but are not limited to, induction motors (IMs), interior permanent magnet motors (IPMs), synchronous reluctance motors (SynRMs), and IPM-SynRM motors. Additionally, outer-rotor / inner-stator motors such as in-wheel motors can benefit from the present invention.

[0010] Stator sleeves are known in the state of the art. For example, U.S. Patent Application Publication No. 2003 / 0193260 teaches a powder metal stator sleeve. Metal stator sleeves are undesirable because of their conductivity and the resulting eddy current losses that reduce motor efficiency.

[0011] U.S. Patent No. 8,378,550 teaches a stator sleeve that is outside the stator windings rather than between the stator and the rotor as in the present invention. Such coolant means are not as efficient as immersing the stator windings in the coolant as in the present invention.

[0012] German Patent No. 102020119110 teaches a stator sleeve that attempts to address the cooling of high-performance electric motors. However, this application improves upon this teaching in many respects, as will be further explained below.

[0013] The purpose of the stator sleeve is to form a barrier between the stator and the rotor of an electric motor, allowing the coolant to flow through the stator for cooling, thereby enhancing the motor efficiency. Therefore, an improved stator sleeve enabling an improved high-performance electric motor is needed. The present invention meets these needs and provides other related advantages.

Prior Art Documents

Patent Documents

[0014]

Patent Document 1

Patent Document 2

Patent Document 3

[0015] Summary of the Invention An exemplary embodiment of the present invention is a method of manufacturing a stator sleeve, the stator sleeve being configured to be assembled as part of a cooled electric motor having a stator with a wound stationary conductor and a rotor with a rotating permanent magnet, the coolant being configured to cool the wound stationary conductor. The method of manufacturing the stator sleeve includes providing a cylindrical mandrel, winding the cylindrical mandrel with a prepreg tape using automated fiber placement, the automated fiber placement being in-situ consolidation, the prepreg tape including a continuous fiber reinforcement within a polymer matrix, heating the prepreg tape during the automated fiber placement, cooling the wound prepreg tape by waiting for an elapsed time, removing the cylindrical mandrel from the wound prepreg tape to obtain an unfinished cylindrical stator sleeve, trimming each end of the unfinished stator sleeve to obtain a trimmed stator sleeve having a first end opposite a second end, providing a first end ring and a second end ring, the first end ring and the second end ring including a polymer, the polymer of the first and second end rings being the same material as the polymer matrix of the prepreg tape, abutting the first and second end rings respectively against the first and second ends of the trimmed stator sleeve using a cylindrical fixture, and forming a finished stator sleeve configured to be installed in a cooled electric motor by laser welding or fusion bonding a first ring and a second ring respectively to the first end and the second end of the trimmed stator sleeve.

[0016] Next, an alternative embodiment will be described. The winding of the prepreg tape of the continuous fiber reinforcement may be in a hoop wrap orientation. The continuous fiber reinforcement may include S2 glass, IM7 carbon and / or boron. The polymer matrix may include PA, PET, PBT, POM, PPS, PEEK, PAEK and / or PEKK.

[0017] Heating of the prepreg tape during automated fiber placement may include hot gas torch convection heating, laser heating, flash lamp heating, or infrared heating.

[0018] The first and second end rings may include a carbon black filled polymer.

[0019] The status sleeve may be impermeable to the coolant.

[0020] The prepreg tape may be unidirectional.

[0021] The step of removing the cylindrical mandrel from the wound prepreg tape may include cooling and shrinking the cylindrical mandrel to reduce its size. Cooling of the cylindrical mandrel may include flowing a cooled liquid over the cylindrical mandrel.

[0022] The step of removing the cylindrical mandrel from the wound prepreg tape may include dissolving the cylindrical mandrel in a liquid configured to dissolve the material of the cylindrical mandrel.

[0023] The step of removing the cylindrical mandrel from the wound prepreg tape may include folding the cylindrical mandrel.

[0024] An exemplary embodiment of the present invention is a method of manufacturing a status sleeve, the status sleeve being configured to be assembled as part of a cooled electric motor having a stator with a wound stationary conductor and a rotor with a rotating permanent magnet, and the coolant being configured to cool the wound stationary conductor.A method of manufacturing a stator sleeve includes providing a cylindrical mandrel, winding the cylindrical mandrel with a prepreg tape using automated fiber placement, heating the prepreg tape during automated fiber placement, cooling the wound prepreg tape by waiting an elapsed time, removing the cylindrical mandrel from the wound prepreg tape to obtain an unfinished cylindrical stator sleeve, providing an outer mold that forms an outer surface of the finished sleeve, the unfinished cylindrical stator sleeve not being fully consolidated, placing the unfinished cylindrical stator sleeve, inserting a conformable bladder into the composite sleeve, pressurizing the conformable bladder, heating an assembly comprising the outer mold, the unfinished cylindrical stator sleeve, and the conformable bladder such that the unfinished stator sleeve is fully consolidated to obtain a consolidated unfinished stator sleeve, cooling the assembly, removing the consolidated unfinished stator sleeve from the outer mold and removing the conformable bladder, trimming each end of the consolidated unfinished stator sleeve to obtain a trimmed stator sleeve having a first end opposite a second end, providing a first end ring and a second end ring, the first and second end rings comprising a polymer, the polymer of the first and second end rings being the same material as the polymer matrix of the prepreg tape, abutting the first and second end rings against the first and second ends of the trimmed stator sleeve using a cylindrical fixture tool, and forming a finished stator sleeve configured to be installed in a cooled electric motor by laser welding or fusion bonding the first and second rings to the first and second ends of the trimmed stator sleeve, respectively.

[0025] Other features and advantages of the present invention will become apparent from the following more detailed description when taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.

[0026] The accompanying drawings illustrate the present invention.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4A

Figure 4B

Figure 5A

Figure 5B

Figure 6A

Figure 6B

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Mode for Carrying Out the Invention

[0028] Composite materials have literally blazed a trail in their adoption by commercial aircraft, one step at a time. At each stage, composites have proven capable of increasingly forming the flight-critical components that have the required strength and stiffness and, in the future, will have few, if any, defects (surface pores and invisible internal voids) that could cause damage as the aircraft ages. Until relatively recently, this near-void-free criterion (porosity less than 1%) was maintained by a combination of vacuum bag consolidation and exposure to high heat and pressure for hours in an autoclave, usually during the curing process. In recent years, the development of oven-curable resins (systems that can be consolidated to an acceptable void content without an autoclave) has helped reduce both the curing cycle time and the time and cost required for part manufacturing, since ovens are less expensive to operate than autoclaves. In parallel, automated filament winding, automated tape laying (ATL), and automated fiber placement (AFP) equipment have replaced manual layup in many applications, significantly increasing the speed at which parts are laminated. These systems are equipped with rollers that compress the material immediately after placement to ensure adhesion and avoid the formation of air pockets that would create voids, but the consolidation of the laminate is still typically done in a second step of a two-step process under a vacuum bag, using another heating device such as an autoclave, oven, or heated tool. This state-of-the-art persists, at least in part, because today's certified aircraft composite materials are predominantly thermosetting.

[0029] There is an alternative. It is known as in-situ consolidation, which means consolidation in place. What is important is to use a thermoplastic matrix instead of a thermosetting matrix. Thermoplastic materials are liquid up to their melting temperature when heated and solidify when cooled, without the need to crosslink like thermosetting resins. Then, the consolidation of thermoplastic composites (TPCs) can be achieved by rapidly heating the impregnated reinforcement to the melting temperature of the thermoplastic polymer matrix and then applying pressure when the tape or tow is placed on the tool and / or previously placed laminate. True in-situ consolidation (ISC) is a one-step process and no further heating or pressurization steps are required after fiber placement or tape laying is complete.

[0030] The implications of eliminating the entire expensive step in the manufacturing process are so significant and obvious that some may wonder why no one has done it yet. For one (there are other reasons to be discussed), the aerospace industry pays a very high price for change. Substituting materials necessarily requires large-scale and costly testing and re-certification.

[0031] That being said, two-step consolidated TPCs are already being used in some aircraft applications. Although their processing temperature is much higher than that of thermosetting resins - nearly 400°C compared to 180°C / 350°F for basic structures - TPCs only require cooling, not crosslinking, so their cycle time is much shorter. Thermoplastics are also inherently tough and do not require special formulations to provide the fatigue resistance required for aircraft applications. Additionally, since thermoplastics can be reheated and reformed, they can be welded (an assembly option that does not use cost-reducing fasteners). As the aircraft industry pursues production rates of at least 60 aircraft per month and materials and processing methods that support the envisioned digital manufacturing, multifunctional structures, and sustainability required for next-generation aircraft, TPCs have emerged as one of the top candidates. TPCs have been selected as the material in a significant proportion of recently completed large-scale aircraft demonstration projects.

[0032] The inventors of the present invention have extensive experience in the aerospace industry and understand that the automation of the manufacturing process of thermoplastic resins by automated tape placement (ATP) can achieve improvements in productivity, reduction in labor costs, and improvement in geometric reproducibility compared to conventional hand lay-up. The inventors have focused on the improvement of electric motors used in a wide range of high-performance applications.

[0033] The present invention incorporates end features to facilitate connection to the stator, fluid sealing, and ease of assembly, and optionally incorporates axial features on the outer diameter for ease of assembly, coolant flow paths, stator winding spacers, and reinforcing members, enables the entire structure to be co-bonded, provides excellent coolant / solvent resistance, enables high-speed manufacturing, enables recycling after life, adopts a thermoplastic polymer composite material, provides an innovative manufacturing method that simplifies the manufacture of an optimized stator sleeve, and improves the prior art by efficiently and rapidly manufacturing a complex stator sleeve assembly.

[0034] As described above, the purpose of the stator sleeve is to create a barrier between the stator and the rotor of an electric motor so that coolant can flow through the stator for cooling. A general configuration is shown in FIG. 1, which is an enlarged cross-sectional view of a diagram of an interior permanent magnet (IPM) motor. FIG. 1 shows a cross-sectional view of an electric motor 10 having an outer housing 11, a stator 12, windings 13, a rotor 14, a rotor sleeve 15, a stator sleeve 16, and permanent magnets 17. It is understood that some electric motors may include a stator sleeve but not have a rotor sleeve.

[0035] The status sleeve 16 of the present invention is ideally formed to be thin. This makes the gap between the stator and the rotor smaller, improving the efficiency. The status sleeve has high strength and rigidity. This allows the wall thickness to be made thinner and minimizes deformation of the sleeve during use. Since the status sleeve has no permeability to the coolant, fluid leakage through the status sleeve material is not a problem. The status sleeve has a low magnetic permeability and thus does not disrupt the magnetic field between the rotor and the stator. The status sleeve also has low conductivity, resulting in low electrical losses due to eddy currents. The status sleeve incorporates features such as end fittings for connection and sealing to the stator, coolant flow paths, reinforcement, structures for integration with the stator windings, and mounting structures for facilitating assembly, alignment, etc.

[0036] It will be understood by those skilled in the art reading this disclosure that since any leakage of coolant can lead to motor failure, the liquid permeability of the stator of the present invention is zero.

[0037] Furthermore, the carbon fiber, glass fiber, and / or polymer composite materials of the present invention do not contribute to magnetic losses in an electric motor. More specifically, glass fibers such as S2 glass are excellent electrical insulators like polymers and do not contribute to the electrical losses of an electric motor. Carbon fibers are conductive (about 2 - 20 microohm-m) along the length direction of the fiber. However, the continuous carbon fiber composite used in the present invention is insulated from each other by the polymer matrix, so there is no conductive path for eddy current losses.

[0038] The present invention includes innovative materials and manufacturing methods for improving the state-of-the-art of status sleeves. The basic approach is to use advanced thermoplastic composite materials in an innovative manufacturing method to produce an improved stator structure.

[0039] The general approach of the present invention is to first manufacture the tube body using a process such as automated fiber placement (AFP) that can be in-situ consolidation (ISC), to manufacture a cylindrical sleeve structure. Then, any additional features such as end fittings and / or axial structures can be incorporated.

[0040] The present invention starts with the manufacture of a composite sleeve. Continuous fiber reinforcements such as S2 glass, IM7 carbon, boron, or any other suitable fiber can be used. Higher strength and stiffness continuous fibers are preferred. The polymer matrix is used to hold the fibers in place within the status sleeve, protect the fibers, transmit structural loads between the fibers, and prevent the permeation of coolants. Thermoplastic polymers are preferred due to their ability to thermally co-bond with other features, coolant resistance, and recyclability. Suitable polymers include, but are not limited to, PA, PET, PBT, POM, PPS, PEEK, PAEK, PEKK, depending on the use temperature and other factors.

[0041] Figure 2A is a photograph of the in-situ consolidation (ISC) process. Figure 2B is a simplified side view similar to the view of Figure 2A showing the in-situ consolidation process. The incoming tape 20 is first guided between one or more tape feed rollers 21. The tape is finally placed on a tool 22 where a number of plies 23 are arranged. As the tape passes through the feed rollers, the tape is finally fed onto the tool or onto a previous ply by a roller 24, and the roller 24 applies a force 25 that presses the tape onto the tool or onto a previous ply. The direction of travel is indicated by arrow 26. This means that the tool is moving in one direction, the roller is moving in the other direction, or a combination of both. A high-temperature gas torch convection heater 27 is used to heat the prepreg tape 20. When a sufficient amount of ply layers are placed, the tape is cut by a tape cutter 28.

[0042] Reinforced thermoplastic composites such as S2 / PEEK are used, but not limited to, using existing state-of-the-art AFP and ISC technologies to manufacture composite cylinders. To obtain high compressive strength, unidirectional composite prepreg tapes along the hoop wrap direction are mainly recommended. This means that the continuous length of the fiber is along the circumference of the cylinder. The ISC process is shown in Figure 2A which forms the cylinder along with the process illustration of Figure 2B. This figure shows high-temperature gas torch (HGT) heating technology, but lasers, flash lamps, IR heaters, or other suitable heating methods can also be used similarly.

[0043] After the composite cylinder is consolidated, the composite cylinder is removed from the mandrel and trimmed to the desired length. Removal of the composite sleeve from the mandrel is facilitated by cooling the mandrel, and such cooling can be incorporated into the mandrel using, for example, a refrigerant. Note that in the ISC process, unlike autoclave consolidation where the mandrel is heated with the part, a release agent is usually not required. The mandrel never reaches the polymer melting temperature that would prevent bonding. In the inventor's experience, an inexpensive aluminum mandrel is preferred due to its high CTE for removing the part after cooling.

[0044] Figure 3 is an embodiment of a cylindrical sleeve 18 removed from a cylindrical mandrel 22.

[0045] Similarly, a collapsible or dissolvable mandrel may be used. A collapsible or dissolvable mandrel may be used, but is generally not necessary in the ISC process. PLA (polylactic acid), eutectic salts, or any other suitable dissolvable mandrel may be used if removal is not possible by other means.

[0046] Alternatively, non-consolidated sleeve preforms may be made using braiding, 3D braiding, knitting, or other textile processes. For sleeve preforms, instead of the ISC process, vacuum bags, shrink wrap tapes or other suitable means may be used for consolidation. However, braiding or other textile weaving processes require thicker laminates because they reduce the compressive strength of the composite cylinder due to fiber undulations.

[0047] Figure 4A shows a consolidation roller 30 with slots. The slotted roller is used to form axial ribs 40. The slotted roller rolls along the longitudinal direction of a sleeve 18 whose curvature 31 matches the outer diameter of the sleeve. There is an annular gap 32 that forms the axial rib 40. In other words, the axial rib 40 on the outer diameter of the status sleeve 18 is formed using an in-situ process where a pure polymer is melted onto the outer diameter of the sleeve and a square cross-sectional shape is formed using the annular gap 32 by the roller. Heat is applied to the neat material and the outer diameter of the status sleeve to melt-bond them. The roller also applies the compressive force necessary to press the neat material against the sleeve to allow for intimate contact for molecular chain entanglement.

[0048] Figure 4B shows that in the ISC process, axial features 40 (such as status slots) can be added using the slots of the consolidation roller or other shaped grooves together with additional composite material or polymer filaments.

[0049] Alternatively, additive manufacturing processes such as fused filament fabrication (FFF) can be used to add features. These features can be added using continuous fiber composites, chopped fiber fills, or neat polymer filaments.

[0050] Furthermore, status slots may be filled with insulators such as PEEK polymer inserts for electrical insulation. Such slot fillers are effective to incorporate into the status sleeve for the additional advantage of increasing the flexural rigidity.

[0051] A trimming operation may be required to trim each end of the unfinished status sleeve 18 to obtain a trimmed status sleeve having a first end 18a that faces the second end 18b.

[0052] To complete the status sleeve ready for production, it is necessary to configure the ends of the stator to operate within a specific motor. This means that various features and structures are required along the ends of the status sleeve. In the present invention, end rings or other features can be added by fusion bonding or other means. FIGS. 5A and 5B show two representative end rings 51 and 52 that can be attached to the status sleeve.

[0053] FIG. 6A is an enlarged cross-sectional view showing the structure of FIG. 5A (end ring 51) attached to one end 18a of the status sleeve 18. Similarly, FIG. 6B is an enlarged cross-sectional view showing the structure of FIG. 5B (end ring 52) attached to the other end 18b of the status sleeve 18. The overlap between the status sleeve and the end fixture can be seen.

[0054] FIG. 7 shows the end rings 51, 52 disposed with respect to the status sleeve 18 using a cylindrical fixture 60 here. The fixture serves to align and hold the end ring in a fixed position with respect to the status sleeve. For example, the tool 60 has a large-diameter portion 61 that abuts against the end ring 51 when the end ring 51 is first slid. Next, the status sleeve can be slid. Finally, the end ring 51 can be slid onto the tool 60. In this way, all three parts are held together in an abutting relationship. Thereafter, the end ring can be joined to the sleeve using a laser welder 70 or the like as shown.

[0055] Figure 8 is a front view of the structure of Figure 7, where the laser welder 70 is applying laser energy 71 to the end fixture and the status sleeve. The laser energy 71 is applied to the status sleeve 18 and the end ring 52, and it can be seen that these are permanently connected to each other.

[0056] Figure 9 is a side view of the laser welding of the end fixture shown in Figure 8. The laser beam 71 is shown directed towards the end fixture and the roller. The roller 72 serves to facilitate the connection between the end ring and the status sleeve. The roller applies a consolidation pressure to the sleeve and the ring. To melt-bond the plastics together, it is necessary to apply both heat and pressure. The laser energy melts the surface, and the roller applies the pressure necessary to bond the two parts together. Those skilled in the art will understand that the end ring can be permanently connected to the status sleeve by other techniques such as fusion bonding or friction welding.

[0057] In Figures 8 and 9, the status sleeve typically has a yellowish-brown color indicating the natural color of the S2 / PEEK composite, and the end fixture is a darker color (such as black), indicating that it is PEEK filled with an IR-absorbing material such as carbon black. S2 / PEEK is transparent to IR lasers, but PEEK filled with carbon black absorbs IR laser energy, so the surface of the PEEK filled with carbon black is heated, enabling fusion bonding to the S2 / PEEK sleeve.

[0058] Figure 10 shows the completed status sleeve assembly 16. One advantage of the present invention is that the polymer used to manufacture the end ring and the polymer used in the prepreg polymer matrix can be the same material. This enables a good connection between the status sleeve and the end ring, whether by laser welding or fusion bonding.

[0059] Figure 11 shows an alternative form of manufacturing the status sleeve of the present invention using bladder molding.

[0060] Bladder forming is an alternative consolidation technique. The idea is to start with a composite sleeve 80 that does not need to be fully consolidated. Such a sleeve may be, for example, partially an ISC (in-situ consolidation) or a braided sleeve.

[0061] The manufacturing process may include the following steps. First, a composite sleeve preform 80 is manufactured. Step A shows inserting a conformable bladder 81 into the composite sleeve 80. Then, the sleeve and bladder are inserted into molds 82, 83. Step B shows pressurizing 84 the bladder to shape the sleeve to the shape of molds 82 and 83. Step C shows heating 85 the assembly until it exceeds the polymer melting temperature. This heat is applied while under pressure. Then, as shown in step D, the assembly is cooled 86 and the consolidated part and bladder are removed from the mold. FIG. 11 is for illustrative purposes only because the cavity has a simple shape, but those skilled in the art will understand that the shape may be cylindrical or any other shape.

[0062] FIGS. 12-16 are perspective views that better depict the process described in FIG. 11. FIG. 12 is a perspective view of very simple molds 82 and 83. This is a two-piece mold, but it can include any number of parts and sections. When pressurization and heating are complete, the inside of the mold forms a surface 87 that ultimately forms the outer surface of the sleeve 80. FIG. 13 shows adding the sleeve 80 and inserting a conformable bladder 81 inside the sleeve. FIG. 14 shows adding the upper mold 83 and then pressurizing 84 and heating 85 the conformable bladder 81. After sufficient time to complete the formation of the sleeve, FIG. 15 shows cooling 86 the assembly and that the bladder 81 may be depressurized. FIG. 16 shows that the upper mold 83 can be removed and then the bladder can be removed. Then, the sleeve 80 can be removed. It should then be understood that, as described above, the sleeve 80 can be trimmed and end rings can be added as described above.

[0063] This method has advantages, which will be described next. The internal pressure and the resulting expansion tend to remove wrinkles in the fibers, thereby improving the compressive strength and tensile strength. This process fully densifies the laminate, reduces the porosity, and eliminates the permeability. If excess polymer or filled polymer is available, external features such as ribs, end rings, or other features can be formed.

[0064] The bladder may be made of different materials depending on temperature, expansion, and other factors. The bladder can be made of an elastomer such as silicone, a metal such as aluminum, or a polymer with a higher melting temperature such as polyimide.

[0065] The bladder can be biased in various ways. First, the bladder can be biased by internal pressure such as air pressure or pneumatic pressure. Second, the bladder can be biased by an applied force using various structures, clamps, and / or weights. Third, the structure can be biased by using a material with a higher coefficient of thermal expansion (CTE) compared to the surrounding structure.

[0066] For example, a glass fiber / PA composite cylinder may be bladder molded using a silicone bladder pressurized with air. Alternatively, it would be possible to use a solid silicone cylinder instead of a bladder, but in this case, since the CTE of silicone is high (assuming the mold is made of steel with a lower CTE), it would be pressurized at the melting temperature of PA. In the case of a glass fiber / PEEK cylinder, since the silicone bladder decomposes at a temperature higher than the temperature required to melt PEEK (>343°C), a higher temperature bladder such as PI or aluminum would be required. Alternatively, it would be possible to use a solid aluminum cylinder instead of a bladder, but in this case, since the CTE of aluminum is high (assuming the mold is made of steel with a lower CTE), it would be pressurized at the melting temperature of PEEK.

[0067] Although several embodiments have been described in detail for purposes of illustration, various modifications can be made to each without departing from the scope and spirit of the invention. Accordingly, the invention is not limited except as by the appended claims.

Explanation of Signs

[0068] 10 Electric motor 11 Outer housing 12 Stator 13 Coil 14 Rotor 15 Rotor sleeve 16 Stator sleeve 17 Permanent magnet 18 Sleeve and stator before completion 20 Tape, prepreg 21 Tape feed roller 22 Tool, mandrel 23 Ply, plies 24 Roller 25 Force 26 Direction of travel 27 Heater, high-temperature gas torch convection heater 28 Tape cutter 30 Consolidation roller with slots 31 Curvature 32 Annular gap 40 Axial feature / rib, stator sleeve 51 End ring, stator sleeve 52 End ring, stator sleeve 60 Cylindrical fixture 70 Laser welder 71 Laser energy 72 Roller 80 Composite sleeve preform 81 Conformable bladder 82 Mold, bottom 83 Mold, top 84 Pressure 85 Heat 86 Cooling 87 surfaces, inside of the mold, outside of the sleeve

Claims

1. A method of manufacturing a stator sleeve configured to be assembled as part of a cooled electric motor having a stator with a wound stationary conductor and a rotor with a rotating permanent magnet, wherein the coolant is configured to cool the wound stationary conductor, comprising: providing a cylindrical mandrel; wrapping the cylindrical mandrel with a prepreg tape using automated fiber placement, wherein the automated fiber placement is in-situ consolidation; wherein the prepreg tape comprises a continuous fiber reinforcement within a polymer matrix; heating the prepreg tape during the automated fiber placement; cooling the wrapped prepreg tape by waiting for an elapsed time; removing the cylindrical mandrel from the wrapped prepreg tape to obtain an unfinished cylindrical stator sleeve; trimming each end of the unfinished stator sleeve to obtain a trimmed stator sleeve having a first end opposite a second end; providing a first end ring and a second end ring, wherein the first end ring and the second end ring comprise a polymer; wherein the polymer of the first and second end rings is the same material as the polymer matrix of the prepreg tape; using a cylindrical fixture to abut the first and second end rings to the first and second ends of the trimmed stator sleeve, respectively; forming a finished stator sleeve configured to be installed in the cooled electric motor by laser welding or fusion bonding the first and second rings to the first and second ends of the trimmed stator sleeve, respectively. A method comprising the above steps.

2. The method of claim 1, wherein the wrapping of the prepreg tape with the continuous fiber reinforcement is in hoop wrap orientation.

3. The method of claim 1 or 2, wherein the continuous fiber reinforcement comprises S2 glass, IM7 carbon, and / or boron.

4. The method according to any one of claims 1 to 3, wherein the polymer matrix comprises PA, PET, PBT, POM, PPS, PEEK, PAEK, and / or PEKK.

5. Heating of the prepreg tape during automated fiber placement is by hot gas torch convection heating, laser heating, flash lamp heating or infrared heating, the method according to any one of claims 1 to 4.

6. The first and second end rings include a carbon black filled polymer, the method according to any one of claims 1 to 5.

7. The status sleeve is impermeable to the coolant, the method according to any one of claims 1 to 6.

8. The prepreg tape is unidirectional, the method according to any one of claims 1 to 7.

9. The step of removing the cylindrical mandrel from the wound prepreg tape includes cooling the cylindrical mandrel to shrink it and reduce its size, the method according to any one of claims 1 to 8.

10. Cooling of the cylindrical mandrel includes flowing a cooled liquid over the cylindrical mandrel, the method according to claim 9.

11. The step of removing the cylindrical mandrel from the wound prepreg tape consists of dissolving the cylindrical mandrel in a liquid configured to dissolve the material of the cylindrical mandrel, the method according to any one of claims 1 to 10.

12. The step of removing the cylindrical mandrel from the wound prepreg tape includes the step of folding the cylindrical mandrel, the method according to any one of claims 1 to 11.

13. A method of manufacturing a status sleeve configured to be assembled as part of a cooled electric motor having a stator with a wound stationary conductor and a rotor with a rotating permanent magnet, the coolant being configured to cool the wound stationary conductor, comprising: providing a cylindrical mandrel; wrapping the cylindrical mandrel with a prepreg tape using automated fiber placement, wherein the automated fiber placement is in-situ consolidation; the prepreg tape includes continuous fiber reinforcements within a polymer matrix; the winding of the prepreg tape of the continuous fiber reinforcements is in hoop wrap orientation; the continuous fiber reinforcements include S2 glass, IM7 carbon and / or boron; the polymer matrix includes PA, PET, PBT, POM, PPS, PEEK, PAEK and / or PEKK; A step of heating the prepreg tape during the automatic fiber placement, wherein the heating includes high-temperature gas torch convection heating, laser heating, flash lamp heating or infrared heating, and the step; A step of cooling the wound prepreg tape by waiting for an elapsed time; A step of removing the cylindrical mandrel from the wound prepreg tape to obtain an unfinished cylindrical status sleeve; A step of trimming each end of the unfinished status sleeve to obtain a trimmed status sleeve having a first end on the opposite side of the second end; A step of providing a first end ring and a second end ring, wherein the first and second end rings contain a polymer, and the step; The first and second end rings contain a carbon black filled polymer; The polymer of the first and second end rings is the same material as the polymer matrix of the prepreg tape; A step of abutting the first and second end rings against the first and second ends of the trimmed status sleeve respectively using a cylindrical fixture; A step of forming a finished status sleeve configured to be installed in a cooled electric motor by laser welding or fusion bonding the first and second rings to the first and second ends of the trimmed status sleeve respectively; A method including.

14. A method of manufacturing a status sleeve configured to be assembled as part of a cooled electric motor having a stator with a wound stationary conductor and a rotor with a rotating permanent magnet, wherein the coolant is configured to cool the wound stationary conductor, the method comprising: A step of providing a cylindrical mandrel; A step of winding a prepreg tape around a cylindrical mandrel using an automatic fiber placement; The prepreg tape includes a continuous fiber reinforcement within a polymer matrix; A step of heating the prepreg tape during the automatic fiber placement; A step of cooling the wound prepreg tape by waiting for an elapsed time; A step of removing the cylindrical mandrel from the wound prepreg tape to obtain an unfinished cylindrical status sleeve; The unfinished cylindrical status sleeve is not fully consolidated, providing an outer profile that forms the outer surface of the finished sleeve; placing the unfinished cylindrical status sleeve; inserting a conformable bladder into the composite sleeve; pressurizing the conformable bladder; heating an assembly comprising the outer profile, the unfinished cylindrical status sleeve, and the conformable bladder, wherein the unfinished status sleeve is fully consolidated to obtain an unfinished status sleeve; cooling the assembly; removing the unfinished status sleeve from the outer profile and removing the conformable bladder; trimming each end of the unfinished status sleeve to obtain a trimmed status sleeve having a first end opposite a second end; providing a first end ring and a second end ring, wherein the first and second end rings comprise a polymer; the polymer of the first and second end rings is the same material as the polymer matrix of the prepreg tape; using a cylindrical fixture to abut the first and second end rings against the first and second ends of the trimmed status sleeve, respectively; forming a finished status sleeve configured to be installed in the cooled electric motor by laser welding or fusion bonding the first and second rings to the first and second ends of the trimmed status sleeve, respectively; A method comprising.

15. The method according to claim 14, wherein the winding of the prepreg tape of the continuous fiber reinforcement is in a hoop wrap orientation.

16. The method according to claim 14 or 15, wherein the continuous fiber reinforcement comprises S2 glass, IM7 carbon and / or boron.

17. The method according to any one of claims 14 to 16, wherein the polymer matrix comprises PA, PET, PBT, POM, PPS, PEEK, PAEK and / or PEKK.

18. The method according to any one of claims 14 to 17, wherein the heating of the prepreg tape in the automatic fiber placement includes high-temperature gas torch convection heating, laser heating, flash lamp heating, or infrared heating.

19. The method according to any one of claims 14 to 18, wherein the first and second end rings comprise a carbon black filled polymer.

Images